Vacuum cleaner

ABSTRACT

The invention provides a vacuum cleaner having a dirty air inlet, a clean air outlet and dirt and dust separating apparatus lying in an air flow path therebetween, wherein the air flow path has a substantially uniform cross-sectional area between the dirty air inlet and the separating apparatus and between the separating apparatus and the clean air outlet. The uniformity of the cross-sectional area reduces frictional losses and reduces pressure drops within the cleaner. Some portions of the air flow path are preferably removable from the cleaner to allow access for maintenance and removal of blockages.

This application claims priority to International Application No.PCT/GB99/03268 which was published on Apr. 20, 2000.

TECHNICAL FIELD OF THE INVENTION

The invention relates to a vacuum cleaner. Particularly, but notexclusively, the invention relates to an upright vacuum cleaner.

BACKGROUND OF THE INVENTION

An upright vacuum cleaner generally has a cleaner head rotatably mountedon the lower end of a main body in which dust separation apparatus ishoused. The dust separation apparatus can be in the form of aconventional bag filter or in the form of a cyclonic separatorconsisting of one or two cyclones as shown and described in, forexample, EP 0 042 723. A handle for propelling the cleaner across thefloor to be cleaned is arranged to extend upwardly from or behind themain body. A pair of supporting wheels are mounted on the lower end ofthe main body or on the cleaner head. The cleaner head extends in aforward direction. A dirty-air inlet is located at the forward end ofthe cleaner head and facing downwardly so that, in use, the dirty-airinlet faces towards the surface to be cleaned. Dirty air is drawn intothe dust separation apparatus via the dirty-air inlet by means of a fandriven by a motor. It is conducted to the dust separation apparatus by afirst air flow path. When the dirt and dust entrained within the air hasbeen separated from the airflow in the separating apparatus, clean airis conducted to the clean air outlet via a second air flow path andexpelled into the atmosphere.

Upright vacuum cleaners are commonly convertible into cylinder cleaners.In the cylinder mode, the dirty air is drawn into the cleaner by way ofa wand or hose attached to the vacuum cleaner instead of by way of thedirty air inlet located in the cleaner head. This cylinder modefacilitates cleaning of areas which cannot be easily reached by thecleaner head, for example, underneath furniture, on stairs or above thefloor. The handle which is used to propel the vacuum cleaner across thefloor in the upright mode is in some cases convertible into a wand andhose arrangement for this purpose. In either mode, the air which isdrawn into the machine has to travel along an air flow path ofsignificant length before being expelled to the atmosphere.

In the known prior art, the air flow path changes in cross-sectionalsize and shape whilst conducting the air from the dirty air inlet to thedirt and dust separating apparatus and then to the clean air outlet ofthe vacuum cleaner. The air flow path also normally follows a routewhich forces the air flow path to change direction abruptly or else toexpand in cross-sectional area. This is because the shape andcross-sectional area of different portions of the air flow paths areoften determined by the relative proportions of different parts of thevacuum cleaner. For example, the portion of the air flow pathimmediately downstream of the changeover valve which selects the dirtyair inlet appropriate to upright cleaning or cylinder cleaning is oftensignificantly larger in cross-section than other portions of the airflow path so that incoming air from either inlet can be accepted intothe downstream flow path. These variations in cross-section of the airflow path cause frictional losses resulting in pressure drops within theair flow, which results in reduced performance of the vacuum cleaner.Air flow paths in prior art vacuum cleaners have also included sharpbends and corners, which also contribute to frictional losses andpressure drops.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a vacuum cleaner inwhich frictional losses and pressure drops are minimised. It is afurther object of the invention to provide a vacuum cleaner having anairflow path which is less prone to blocking and accumulation of dirtand dust than known vacuum cleaners. A still further object is toprovide a vacuum cleaner in which the parts of the airflow path whichare prone to blocking are more easily accessible than in known vacuumcleaners.

The uniform cross-sectional area of the air flow path ensures thatfrictional losses and pressure drops are kept to a minimum and that thedust separation apparatus may thus function at maximum efficiency. Thepreferred circular cross-sectional area of substantially 800 mm² hasbeen found to be particularly effective when the vacuum cleaner includesdust separation apparatus consisting of a cyclonic separator.

The provision of removable portions housing curved parts of the air flowpath allows the user of the apparatus to remove the removable portionsshould any blockages occur in the said curved portions. The removal of aremovable portion gives the user of the apparatus easy access to the airflow path which allows removal of blockages quickly and easily. Theremovable portions are preferably retained in an operational positionwith respect to the remainder of the apparatus by quick releasefastenings, for example, resilient tabs, to enable an unskilled user ofthe apparatus to carry out basic maintenance and removal of blockages.This reduces the amount of skilled time required to maintain theapparatus and keeps the apparatus operational for longer periods thusincreasing user satisfaction and decreasing the amount of time requiredfor maintenance and repair.

DETAILED DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the apparatus according to the invention willnow be described in detail with reference to the accompanying drawingsin which:

FIG. 1 is a view of a vacuum cleaner according to the invention from oneside;

FIG. 2 is a view of from the other side;

FIG. 3 is a rear view of the vacuum cleaner of FIG. 1; and

FIG. 4 is a second rear view of the vacuum cleaner of FIG. 1 with two ofthe removable portions of the air flow path detached.

BRIEF DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 to 3, a vacuum cleaner 10 according to theinvention has a main body 12 in which dust separation apparatus 14 islocated. In the illustrated embodiment, the dust separation apparatuscomprises two cyclones arranged in series. However, the nature of thedust separation apparatus 14 is not material to the present inventionand the separation of dust from the airflow could equally be carried outusing other means such as a conventional bag-type filter. A motorhousing 16 is located at the lower end of the main body 12 and a cleanerhead 18 is rotatably mounted on the motor housing 16. The cleaner head18 has a brush housing 20 in which a rotatable brush bar is housed foruse during upright cleaning. The brush bar is mounted in the mouth of afirst dirty air inlet in the cleaner head 18. A motor and fanarrangement (not shown) is housed within the motor housing and supportwheels 22 are mounted thereon. Extending upwardly from the motor housing16 and alongside the main body 12 is a handle 24 which can be releasedfrom a socket 26 so as to allow it to be used as a hose/wand structure.The handle 24 consists of a wand 24 a surrounded by a hose 24 b. Asecond air inlet, which is normally closed by a cap 28, is located inthe distal end of the wand 24 a which also carries a hand grip 30.Additional tools 32 are releasably carried on the handle 24 and on theupper end of the main body 12 for use during above floor cleaning. Thistype of vacuum cleaner, and other similar arrangements, are well knownin the marketplace.

The vacuum cleaner 10, as will be understood from the above briefdescription, has two alternative dirty air inlets; one in the cleanerhead 18 and the other at the distal end of the wand 24 a. The dirty airinlet to be used at any one time will depend upon the mode of operationin which the cleaner 10 is being used. When the cleaner 10 is being usedin the upright mode, the operational air inlet is the one in the cleanerhead 18. When the cleaner 10 is being used for above the floor cleaning,the air inlet in the distal end of the wand 24 a is brought intooperation. The cleaner 10 incorporates a changeover valve (not shown)which automatically selects the appropriate air inlet in dependence uponthe angle of inclination of the handle 24 to the vertical. It will beappreciated that, when the cleaner 10 is to be used in the upright mode,the handle 24 will be inclined to the vertical and, when the cleaner 10is to be used in the cylinder mode, the handle 24 will be in thevertical position shown in FIGS. 1 and 2.

When the cleaner 10 is to be used in the upright mode, the air inlet inthe cleaner head 18 becomes operational. Dirty air is drawn into thebrush housing 20 through the inlet. A flexible pipe 34 carries the dirtyair from the brush housing 20 through the changeover valve (not shown)and on to a first duct 36. The first duct 36 communicates with a secondduct 38 which extends up the rear of the main casing 12 alongside thehandle 24 to the upper end of the dirt and dust separating apparatus 14.The dirt and dust separating apparatus 14 comprises two cyclonicseparators arranged in series but, since the nature of the separatingapparatus is not material to the invention, the exact operation of thecyclonic separator will not be described in full here. Suffice it to saythat the inlet to the dirt and dust separating apparatus 14 is locatednear the upper end thereof and the outlet of the dirt and dustseparating apparatus is located immediately above the inlet thereto. Athird duct 40 carries air leaving the dirt and dust separating apparatusto the motor casing 16 in which the motor and fan are housed. An airoutlet 42 is positioned beneath the lower end of the main casing 12 andinternal ducting (not shown) carries air from the motor casing to theoutlet 42.

The flexible pipe 34, the first duct 36, the second duct 38 and thethird duct 40 are all circular in cross section. They all have a uniformcross-sectional area of substantially 800 mm², although it is envisagedthat cross-sectional areas of between 600 mm² and 1400 mm² will beequally effective, particularly for different types of machine. In theembodiment illustrated, the diameter of the airflow path is essentially32 mm in the portions in which the cross-sectional area is uniform.Also, the flexible pipe 34 and the first, second and third ducts 36, 38,40 are constructed and arranged so that there are no sharp changes indirection incorporated within the air flow path as a whole. All changesin direction are smoothly curved so that frictional losses in the airflow path are kept to a minimum and pressure drops are reduced. The sameis true for the changeover valve which maintains the constant, smoothairflow path just described as the air passes therethrough.

The third duct 40 conveys the airflow to the motor casing 16 so that theairflow can be used to cool the motor. It will be appreciated that theairflow cannot maintain a uniform cross section around the motor. Forthe purposes of this invention, it is preferred that the motor and fanarrangement be deemed to be placed at the outlet of the flow path andthat the intention of the invention is not to maintain the uniformity ofthe cross-sectional area around the motor whilst the airflow is beingused for cooling purposes.

When the cleaner 10 is to be used in the cylinder mode, the handle 24 isreleased from the socket 26 and the wand 24 a is extended so that theupper end of the hose 24 b is in communication with the lower end of thewand 24 a. The changeover valve shuts off the inlet in the cleaner head18 and brings the inlet in the distal end of the handle 24 intooperation. In this mode, dirty air in drawn into the said inlet andcarried down the wand 24 a and the hose 24 b to a fourth duct 44 whichcarries the dirty air to the changeover valve referred to above. Fromthe changeover valve to the clean air outlet, the passage of the air isas described above. The wand 24 a, the hose 24 b and the fourth duct 44all have an essentially constant cross-sectional area of 800 mm², or anarea equivalent to that of the first, second and third ducts 36, 38, 40.Any changes in direction effected by the wand 24 a or the fourth duct 44are smooth and do not include sharp corners or abrupt changes indirection. The connection between the wand 24 a and the hose 24 b isdesigned to ensure that the hose does not bend suddenly at the junction,although the flexible nature of the hose inevitably allows some changesin direction to take place.

FIG. 4 shows the cleaner 10 of the present invention with the handle 24in a semi-extended position, or as it would be when the cleaner 10 isbeing prepared for above the floor cleaning. The lower end of the wand24 a is released from the socket 26 so that the upper end of the hose 24b can be slid to the lower end of the wand 24 a. This, combined with theextendability of the hose itself, allows the user to access areas at aconsiderable distance from the main body 12 of the cleaner 10. Alsoshown in FIG. 4 is the removable nature of two portions of the air flowpath. The first duct 36 and the fourth duct 44 are each made removablefrom the cleaner 10 to allow blockages to be easily accessed andremoved. Both of the removable portions are positioned upstream of thedust separating apparatus 14 in view of the fact that blockages are lesslikely to occur downstream of the dust separating apparatus 14.

Each removable duct 36, 44 has a resilient tab or tongue 50 whichcooperates with a groove or aperture in or on the main casing 12 (oranother non-removable part of the cleaner 10) for releasably attachingthe removable duct 36, 44 thereto. A seal is also provided around eachend of the portion of the air flow path housed within the respectiveremovable duct 36, 44 to ensure that the connection between that portionwithin the removable duct and the remainder of the air flow path isessentially airtight. The removable portions 36, 44 are those portionsof the air flow path which include the least accessible curves upstreamof the dust separating apparatus 14, or those curve or portions of theairflow path which are most prone to blockage. By making these portionsremovable, the ease with which they can be accessed and unblocked isgreatly increased. The snap-fitting connection of the removable portions36, 44 onto the cleaner 10 means that the removal of the removableportions 36, 44 can be carried out easily and quickly by an unskilleduser so that the amount of interruption to normal use of the cleaner 10is minimal. It will be appreciated that other easily operated connectorscan be provided in place of snap-fit connectors: for example,quick-release quarter-turn fasteners can provide equally adequateconnections.

The dust separating apparatus 14 is also adapted to be releasable fromthe main body 12 of the cleaner 10. The main purpose of this is to allowthe dust separating apparatus 14 to be emptied periodically. However,the removal of the dust separating apparatus 14 allows the user accessto the upper end of the second duct 38 so that any blockages which occurcan be easily removed. This, in combination with the removability of thefirst duct 36, means that the whole of the second duct 38 can be clearedof obstructions should any occur. Removal of the dust separatingapparatus 14 also allows access to the upper end of the third duct 40,although the likelihood of blockages occurring downstream of the dustseparating apparatus 14 is less than that of blockages occurringupstream thereof.

The clearing of blockages from the hose is also facilitated by the factthat the hose 24 b is designed to be easily removable from the socket 26when required by the user. Should the hose 24 b become blocked, the hose24 b can be removed from the socket 26 and accessed from the end whichnormally resides in the socket 26 in order to remove any blockages. Thelower end of the hose will be more prone to blockages than the upperend.

The invention is not limited to the precise details discussed anddescribed above in connection with the illustrated embodiment. Furthermodifications and variations will be apparent to a skilled reader. Forexample, it will be appreciated that the essence of the invention is toprovide an air flow path which maintains an essentially uniformcross-sectional area between the dirty air inlet and the dust separatingapparatus, and between the dust separating apparatus and the outlet ofthe machine. It is immaterial whether or not a motor and fan unit isplaced immediately before the clean air outlet. The inventioncontemplates that the cross-sectional area of the airflow path will beessentially uniform upstream of the motor and fan unit but will alter asnecessary to achieve the cooling effect required for the motor. It willalso be understood that, as in a number of known vacuum cleaners, apre-motor filter may be positioned immediately upstream of the motor toprevent any particles which are not captured by the dust separatingapparatus from entering the motor and causing damage thereto. It is notenvisaged that the air flow path will have a constant or uniformcross-section through the pre-motor filter, but that the uniform portionof the air flow path will cease immediately before the pre-motor filter.In other arrangements, the pre-motor filter is arranged immediatelydownstream of the dust separating apparatus and is effectively integraltherewith.

What is claimed is:
 1. A vacuum cleaner having a first dirty air inletlocated in a cleaner head incorporating a brush housing, a clean airoutlet, an air flow path extending between the first dirty air inlet andthe clean air outlet, dirt and dust separating apparatus lying in theair flow path, a fan and motor unit lying in the air flow pathdownstream of the dirt and dust separating apparatus, a second dirty airinlet, a conduit extending between the second dirty air inlet and aportion of the air flow path upstream of the dirt and dust separatingapparatus, and a changeover valve located and adapted so as toselectively allow dirty air to pass to the dirt and dust separatingapparatus from one of the first and second dirty air inlets,characterized that the air flow path and the conduit have asubstantially uniform cross-sectional area at all locations between thefirst dirty air inlet, downstream of the brush housing, and theseparating apparatus, between the second dirty air inlet and theseparating apparatus, and between the separating apparatus and the fanand motor unit, including through or past the changeover valve. 2.Apparatus as claimed in claim 1, wherein the uniform cross-sectionalarea of the air flow path and conduit is substantially circular. 3.Apparatus as claimed in claim 1, wherein the uniform cross-sectionalarea of the air flow path and conduit is between 600 mm² and 1400 mm².4. Apparatus as claimed in claim 3, wherein the uniform cross-sectionalarea of the air flow path and conduit is substantially 800 mm². 5.Apparatus as claimed in claim 1, wherein each of the air flow path andconduit comprises a plurality of smooth curves and a plurality ofstraight portions.
 6. Apparatus as claimed in claim 5, wherein anysmooth curves forming part of each of the air flow path and conduitupstream of the separating apparatus are housed in removable portions ofthe apparatus.
 7. Apparatus as claimed in claim 1, wherein at least apart of each of the air flow path and conduit is housed within aremovable portion of the apparatus to facilitate maintenance. 8.Apparatus as claimed in claim 7, wherein the or each removable portionof the apparatus is releasably attached to a non-removable housing ofthe apparatus by way of a snap-fit fastening.
 9. Apparatus as claimed inclaim 8, wherein the snap-fit fastening comprises a resilient memberlocated on the removable portion engageable with a cooperating aperturein the housing.
 10. Apparatus as claimed in claim 1, wherein the fan andmotor unit is arranged in the air flow path immediately upstream of theclean air outlet.
 11. Apparatus as claimed in claim 10, wherein apre-motor filter is arranged immediately upstream of the motor orimmediately downstream of the dirt and dust separating apparatus. 12.Apparatus as claimed in claim 11, wherein the dirt and dust separatingapparatus comprises a cyclonic separator.
 13. Apparatus as claimed inclaim 12, wherein the cyclonic separator comprises two cyclones arrangedin series.
 14. Apparatus as claimed in claim 10, wherein the vacuumcleaner is an upright vacuum cleaner.
 15. Apparatus as claimed in claim14, wherein the second dirty air inlet is provided in the form of a hoseor wand.